Regioregular HH-TT poly(3,3′-thioalkylbithiophene)s-bearing branched or linear alkyl side-chain substituents (PT2SR) have been synthesized and characterized to investigate their behavior, when used ...as electron-donor components in blend with a fullerene derivative 6,6-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor, in air-processed photovoltaic solar cells with bulk heterojunction architecture. The optoelectronic characteristics, energy gap, nanoscale morphology, and crystallinity of the blends (PT2SR/PCBM) were examined by ultraviolet–visible spectroscopy, cyclic voltammetry, Kelvin probe force microscopy (KPFM), and X-ray diffraction (XRD). We demonstrate that thioalkyl substituents are able to influence the PCBM self-assembly and the morphology of the polymeric film, important parameters to maximize the efficiency of the solar cell. In particular, the presence of chemical branching in the side chain of the sulfur over-rich polythiophene backbone favors the formation of PCBM clusters, of size of about 100 ± 30 nm, as confirmed by XRD and KPFM measurements. This facilitates the intermixing between donor and acceptor materials at the nanoscale level, determining an increase in the device performance.
Four new conjugated polymers alternating benzothiadiazole units and thiophene moieties functionalized with ionic phosphonium or sulfonic acid salts in the side chains were synthesized by a ...postfunctionalization approach of polymeric precursors. The introduction of ionic groups makes the conjugated polymers soluble in water and/or polar solvents, allowing for the fabrication of bulk heterojunction (BHJ) solar cells using environmentally friendly conditions. All polymers were fully characterized by spectroscopic, thermal, electrochemical, X-ray diffraction, scanning electron, and atomic force techniques. BHJ solar cells were obtained from halogen-free solvents (i.e., ethanol and/or anisole) by blending the synthesized ionic push–pull polymers with a serinol-fullerene derivative or an ionic homopolymer acting as electron-acceptor (EA) or electron-donor (ED) counterparts, respectively. The device with the highest optical density and the smoothest surface of the active layer was the best-performing, showing a 4.76% photoconversion efficiency.
A new side-chain C60-fullerene functionalized thiophene copolymer bearing tributylphosphine-substituted hexylic lateral groups was successfully synthesized by means of a fast and effective ...post-polymerization reaction on a regioregular ω-alkylbrominated polymeric precursor. The growth of the polymeric intermediate was followed by NMR spectrometry in order to determine the most convenient reaction time. The obtained copolymer was soluble in water and polar solvents and was used as a photoactive layer in single-material organic photovoltaic (OPV) solar cells. The copolymer photovoltaic efficiency was compared with that of an OPV cell containing a water-soluble polythiophenic homopolymer, functionalized with the same tributylphosphine-substituted hexylic side chains, in a blend with a water-soluble C60-fullerene derivative. The use of a water-soluble double-cable copolymer made it possible to enhance the control on the nanomorphology of the active blend, thus reducing phase-segregation phenomena, as well as the macroscale separation between the electron acceptor and donor components. Indeed, the power conversion efficiency of OPV cells based on a single material was higher than that obtained with the classical architecture, involving the presence of two distinct ED and EA materials (PCE: 3.11% vs. 2.29%, respectively). Moreover, the synthetic procedure adopted to obtain single material-based cells is more straightforward and easier than that used for the preparation of the homopolymer-based BHJ solar cell, thus making it possible to completely avoid the long synthetic pathway which is required to prepare water-soluble fullerene derivatives.
The Internet of Things (IoT) is a complex ecosystem of connected devices that exchange data over a wired or wireless network and whose final aim is to provide services either to humans or machines. ...The IoT has seen rapid development over the past decade. The total number of installed connected devices is expected to grow exponentially in the near future, since more and more domains are looking for IoT solutions. As a consequence, an increasing number of developers are approaching IoT technology for the first time. Unfortunately, the number of IoT-related studies published every year is becoming huge, with the obvious consequence that it would be impossible for anyone to predict the time that could be necessary to find a paper talking about a given problem at hand. This is the reason why IoT-related discussions have become predominant in various practitioners’ forums, which moderate thousands of posts each month. The present paper’s contribution is twofold. First, it aims at providing a holistic overview of the heterogeneous IoT world by taking into account a technology perspective and a business perspective. For each topic taken into account, a tutorial introduction (deliberately devoid of technical content to make this document within the reach of non-technical readers as well) is provided. Then, a table of very recent review papers is given for each topic, as the result of a systematic mapping study.
Many scholars have reported that the adoption of Model Driven Engineering (MDE) in the industry is still marginal. Real-life case studies, completed with convincing empirical data about the quality ...of the developed source code, is an effective way to persuade the industry that the adoption of MDE brings an actual added value. This paper reports about the assessment of the quality of the code outputted by xGenerator: a Java technology platform for the development of enterprise Web applications, which implements the MDE paradigm. Two recent papers from Aniche and his colleagues were selected to carry out the measurements. The former study is about metrics and thresholds for MVC Web applications, while the latter presents a catalog of six smells tailored to MVC Web applications. A big merit of both of these proposals is that they fix the metric thresholds by taking into account the MVC software architecture. The results of the empirical assessment, carried out on a real-life project, proved that the quality of the code is high.
Hybrid PET/CT scanners can simultaneously visualize coronary artery disease as revealed by computed tomography (CT) and myocardial perfusion as measured by positron emission tomography (PET). Manual ...registration is usually required in clinical practice to compensate spatial mismatch between datasets. In this paper, we present a registration algorithm that is able to automatically align PET/CT cardiac images. The algorithm bases on mutual information (MI) as registration metric and on genetic algorithm as optimization method. A multiresolution approach was used to optimize the processing time. The algorithm was tested on computerized models of volumetric PET/CT cardiac data and on real PET/CT datasets. The proposed automatic registration algorithm smoothes the pattern of the MI and allows it to reach the global maximum of the similarity function. The implemented method also allows the definition of the correct spatial transformation that matches both synthetic and real PET and CT volumetric datasets.
In poly(thiophene) (PT) block copolymers, aggregation features can be transferred from one block to the other. In this paper, it is investigated whether this is also possible in block copolymers ...consisting of blocks with different electronic properties, i.e. PT and poly(fluorene) (PF), in order to obtain a polymer with a unique combination of aggregation properties. By combining a PT block with chiral side chains with a PF block with linear octyl side chains, it is probed to obtain a polymer in which chiral expression (arising from the PT with chiral side chains) and β-phase aggregation (arising from the PF with linear octyl side chains) are brought together. This combination is not possible in homopolymers, since chiral aggregation implies chiral, branched side chains and β-phase aggregation is only possible for PF with linear side chains. In a stepwise approach, the right conditions are elucidated to obtain both characteristics in one polymer. For this purpose, three block copolymers were synthesized via Suzuki catalyst transfer condensative polymerization (SCTCP), i.e. , poly(9,9-dioctylfluorene)-b-poly(3-((S)-3,7-dimethyloctyl)thiophene) (POF- b -P3OT*), poly(9,9-dihexylfluorene)-b-poly(3-((S)-3,7-dimethyloctyl)thiophene) (PHF- b -P3OT*), and poly(9,9-dioctylfluorene)-b-poly(3-((S)-2-methylbutyl)thiophene) (POF- b -P3BT*), and their aggregation behavior was studied via solvatochromism experiments. It is concluded that the side chains of the PF block should be 8 C atoms long to ensure maximal β-phase aggregation and that the side chains of the PT block should be short to ensure this block aggregates first in a chiral way. In this way, the PT block can transfer its chirality to the PF block and a polymer is obtained in which β-phase aggregation and expression of chirality are combined in one PF, something which is impossible for homopolymers.
Two water-soluble regioregular poly(3-alkylthiophene)s, incorporating aminic groups at the end of the side chains, have been synthesized using a post-polymerization functionalization procedure on a ...ω-bromine substituted polyalkylthiophene. The high solubility of the obtained polymers in water allowed for the preparation of “green” bulk heterojunction solar cells which reached a power conversion efficiency of 4.85% when PC61BM was used as electron-acceptor material. Improved optical absorption and photocurrent have been obtained by interposing a layer of Ag nanoparticles between the buffer and the photoactive layer, leading to a final power conversion efficiency of 5.51%.
3D Optimization of PT6NEt (top) and PT6Pir (bottom) repeating units. Display omitted
•Water-soluble polythiophenes have been synthesized using a reactive polymer precursor.•Polymeric solar cells show satisfactory efficiencies.•An interlayer of Ag nanoparticles can increase the light conversion.
Side‐chain C60‐fullerene functionalized alkylthiophene copolymers with different regioregularity and fullerene content are successfully synthesized using a simple and straightforward ...post‐polymerization functionalization procedure based on a Grignard coupling reaction. The products are employed as single materials in photoactive layers of organic photovoltaic solar cells. The use of double‐cable polymers allows an enhanced control on the nanomorphology of the active blend, reducing the phase‐segregation phenomena as well as the macroscale separation between the electron acceptor and donor components. With the insertion of a thin layer of gold nanoparticles between buffer and active layer of the cells, a conversion efficiency of 5.68% is obtained. Moreover, an increased stability over time is achieved when the copolymers are photocrosslinked immediately after the annealing procedure, leading to acceptable efficiencies even after 80 h of accelerated ageing, a key feature for widespread applicability of the prepared devices.
Different types of bromine‐functionalized polyalkylthiophenes are employed as polymeric precursors for the preparation of double‐cable fullerene‐substituted copolymers. Copolymers' morphology and photoconversion efficiency, when used in single‐material solar cells, are strongly affected by the regiostructural order of the polymeric backbone. Furthermore, UV‐cured photoactive layers exhibit excellent overtime stabilities of the photovoltaic performances.
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